scholarly journals The Use of Oxidative Alkali Treatment for Sulphate Hardwood Pulp Bleaching

2020 ◽  
pp. 168-177
Author(s):  
T. Koroleva ◽  
◽  
L. Milovidova ◽  
G. Komarova ◽  
A. Dryakhlitsyn ◽  
...  
Keyword(s):  
Alkali Treatment ◽  
Pulp Bleaching ◽  
Hardwood Pulp

scholarly journals TOTAL CHLORINE-FREE BLEACHING OF SULFATE HARDWOOD PULP WITH HYDROGEN PEROXIDE

2019 ◽  
pp. 287-294
Author(s):  
Фирдавес (Firdaves) Харисовна (Harisovna) Хакимова (Hakimova) ◽  
Константин (Konstantin) Андреевич (Andreevich) Синяев (Sinyaev)
Keyword(s):  
Hydrogen Peroxide ◽  
Mechanical Strength ◽  
Small Proportion ◽  
Pulp Fibers ◽  
Pulp Bleaching ◽  
Sulfate Pulp ◽  
Environmentally Safe ◽  
Hardwood Pulp ◽  
High Degree ◽  
Pulp Production

The work is devoted to the study of the possibility and feasibility of environmentally safe bleaching of sulfate hardwood pulp by TCF-technology without the use of traditional oxygen and ozone as a delignifying reagent. The TCF-technology of sulphate hardwood pulp bleaching (scheme Pa-EP-Pd-Aac-P-A) was developed with only one oxidizing reagent – hydrogen peroxide. It is proposed to carry out of pulp delignification with hydrogen peroxide in an acid medium conditions, additional delignification and bleaching – with hydrogen peroxide in an alkaline medium conditions. Soft oxidizing effect of hydrogen peroxide used at all stages of bleaching provides selectivity of the process along with ecological compatibility of the scheme. The mechanical strength of pulp varies during bleaching in accordance with the change of the degree of delignification and is very moderate, and the total loss of pulp fibers is only 6.1%. Production of hardwood sulfate pulp, as well as sulfite, is associated with difficulties caused by a "harmful" resin at a small proportion of extractives. The proposed scheme of bleaching provides a high degree of resin removal and contributes to the depitching, i.e. decision of very important problems in sulphate hardwood pulp production.

Ozone-enhanced bleaching of softwood kraft pulp

TAPPI Journal ◽  
2010 ◽  
Vol 9 (8) ◽  
pp. 16-23 ◽  
Author(s):  
JEAN-CHRISTOPHE HOSTACHY
Keyword(s):  
Capital Investment ◽  
Kraft Pulp ◽  
Operating Cost ◽  
Pulp Mill ◽  
Economic Benefits ◽  
Variable Cost ◽  
Pulp Mills ◽  
Pulp Bleaching ◽  
Softwood Kraft Pulp ◽  
Hardwood Pulp

By using ozone in their bleaching processes, many hardwood pulp mills in various parts of the world have improved product quality and their environmental and process performance, and reduced operating costs to increase competitiveness. The challenge for softwood pulp is to rethink the use of ozone according to their specific requirements. This paper summarizes results obtained using ozone bleaching on softwood (Pinus radiata) kraft pulp, for which the brightening ability of limited ozone dosages can enhance the economic benefits without impairing pulp quality. This work evaluated the chemical justification to use ozone at the end of the bleaching sequence and the effect on pulp quality, and considered the practical consequences of this new option. Special attention was given to the economic and technical aspects, including investment cost, variable cost, and process implementation. Ozone was shown to be the ideal complement of chlorine dioxide for final pulp bleaching. Both chemicals can easily be combined at the end of the bleaching sequence. Taking into account pulp mill capacity, capital investment, and total operating cost, the financial savings were calculated to be in the range of EUR 5 million (USD 6 million) per year, with a payback period of about 1.5 years.

Fundamental molecular characterization and comparison of the O, D0, and E stage effluents from hardwood pulp bleaching

TAPPI Journal ◽  
2019 ◽  
Vol 18 (6) ◽  
pp. 341-351 ◽  
Author(s):  
JULIANA JARDIM ◽  
XUEYU DU ◽  
PETER HART ◽  
LUCIAN LUCIA ◽  
HASAN JAMEEL ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Gel Permeation Chromatography ◽  
High Yield ◽  
Lower Amount ◽  
Oxygen Delignification ◽  
Pulp Bleaching ◽  
Dissolved Organics ◽  
Hardwood Pulp

The present study characterized effluents from the O, D0, and E stages using nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC) techniques to better understand the chemical nature of the dissolved organics formed from the bleaching of a high-yield hardwood kraft pulp. Understanding the structures and molecular weight distribution of these organics is the first step in developing methods to mitigate these contaminates in the discharged effluents. The results indicated that the molecular weight distribution (MWD) of the dissolved organics from oxygen delignification effluent is broader than those from D0 and E stage effluents. In addition, the O stage filtrate contained considerable amounts of lignin and xylan fragments, which showed its efficiency in removing such materials. The effluent from the D0 stage contained a lower amount of high molecular weight fragments and a higher amount of low molecular weight fragments versus the O-stage filtrate. Aromatic structures were nearly absent in the D0 stage filtrate, but the degraded organic material, presumably from oxidized lignin, contained olefinic (C=C) and carbonyl (C=O) functional groups. Furthermore, higher molecular weight fragments were detected in the E-stage effluent, presumably due to the extensive solubilization and removal of the oxidized lignin generated from the D0 pulp.

scholarly journals IR SPECTRA AND HEATS OF HYDRATION OF THE OZONATED PULP

2017 ◽  
pp. 13-20
Author(s):  
Ираида (Iraida) Ивановна (Ivanovna) Осовская (Osovskaia) ◽  
Вероника (Veronika) Сергеевна ( Sergeevna) Антонова (Antonova) ◽  
Ольга (Ol'ga) Юрьевна (Iur'evna) Деркачева (Derkacheva) ◽  
Альбина (Al'bina) Васильевна (Vasil'evna) Авакумова (Avakumova)
Keyword(s):  
Chlorine Dioxide ◽  
Structural Changes ◽  
Organochlorine Compounds ◽  
Chemical Research ◽  
Pulp Bleaching ◽  
Modified Method ◽  
Mechanism Of Interaction ◽  
Hardwood Pulp ◽  
The Cost ◽  
Physical And Chemical

Reduce the consumption of chlorine dioxide in the bleaching of pulp is one of the main problems of technology of production of bleached pulp at Russian enterprises. We have developed a modified method of bleaching of sulphate hardwood pulp with a degree of ozonization. The new in work is the identification of the mechanism of ozonation on the structure of cellulose at different stages of the pulp bleaching. To assess structural changes of cellulose in the process of bleaching was used technique  for IR spectroscopy. To characterize the hydrophilic properties of the cellulose used a calorimetric method and the method equilibrium sorption.Shown an advantage of using both chlorine dioxide and ozone in the bleaching of sulphate hardwood pulp. The obtained results of physical and chemical research associated with physico-mechanical properties of bleached and unbleached cellulose at different stages of bleaching. Shows the effect of ozonation on the mechanism of interaction of cellulose with bleaching agents. Effective delignification in the joint use of ozone and chlorine dioxide, can reduce the cost of bleaching chemicals. The brightness level corresponds to the world standards. and the content of organochlorine compounds (AOH) decreased by 30%. Reduce the consumption of chlorine dioxide helps to reduce contamination of waste water, reducing the content of organochlorine compounds (AOH).

scholarly journals Selectivity Studies of Oxygen and Chlorine Dioxide in the Pre-Delignification Stages of a Hardwood Pulp Bleaching Plant

2001 ◽  
Vol 40 (24) ◽  
pp. 5680-5685 ◽  
Author(s):  
Maria J. M. C. Barroca ◽  
Pedro J. T. S. Marques ◽  
Isabel M. Seco ◽  
José Almiro A. M. Castro
Keyword(s):  
Chlorine Dioxide ◽  
Pulp Bleaching ◽  
Selectivity Studies ◽  
Hardwood Pulp

Elemental chlorine-free bleaching of North American hardwood kraft pulps: Evaluation of oxidant-reinforced extraction variables on overall bleaching optimization

TAPPI Journal ◽  
2013 ◽  
Vol 12 (10) ◽  
pp. 33-41 ◽  
Author(s):  
BRIAN N. BROGDON
Keyword(s):  
Response Surface ◽  
Chlorine Dioxide ◽  
North American ◽  
Yield Loss ◽  
Alkaline Extraction ◽  
Kraft Pulps ◽  
Pulp Bleaching ◽  
Response Surface Models ◽  
Elemental Chlorine ◽  
Surface Models

This investigation evaluates how higher reaction temperatures or oxidant reinforcement of caustic extraction affects chlorine dioxide consumption during elemental chlorine-free bleaching of North American hardwood pulps. Bleaching data from the published literature were used to develop statistical response surface models for chlorine dioxide delignification and brightening sequences for a variety of hardwood pulps. The effects of higher (EO) temperature and of peroxide reinforcement were estimated from observations reported in the literature. The addition of peroxide to an (EO) stage roughly displaces 0.6 to 1.2 kg chlorine dioxide per kilogram peroxide used in elemental chlorine-free (ECF) bleach sequences. Increasing the (EO) temperature by Δ20°C (e.g., 70°C to 90°C) lowers the overall chlorine dioxide demand by 0.4 to 1.5 kg. Unlike what is observed for ECF softwood bleaching, the presented findings suggest that hot oxidant-reinforced extraction stages result in somewhat higher bleaching costs when compared to milder alkaline extraction stages for hardwoods. The substitution of an (EOP) in place of (EO) resulted in small changes to the overall bleaching cost. The models employed in this study did not take into account pulp bleaching shrinkage (yield loss), to simplify the calculations.

Use of cold tolerant eucalyptus species as a partial replacement for southern mixed hardwoods

TAPPI Journal ◽  
2012 ◽  
Vol 11 (7) ◽  
pp. 29-35 ◽  
Author(s):  
PETER W. HART ◽  
DALE E. NUTTER
Keyword(s):  
Potential Method ◽  
The United States ◽  
Partial Replacement ◽  
Growth Time ◽  
Eucalyptus Species ◽  
Cold Tolerant ◽  
Hardwood Pulp ◽  
Time Required ◽  
The Cost ◽  
Operational Data

During the last several years, the increasing cost and decreasing availability of mixed southern hardwoods have resulted in financial and production difficulties for southern U.S. mills that use a significant percentage of hardwood kraft pulp. Traditionally, in the United States, hardwoods are not plantation grown because of the growth time required to produce a quality tree suitable for pulping. One potential method of mitigating the cost and supply issues associated with the use of native hardwoods is to grow eucalyptus in plantations for the sole purpose of producing hardwood pulp. However, most of the eucalyptus species used in pulping elsewhere in the world are not capable of surviving in the southern U.S. climate. This study examines the potential of seven different cold-tolerant eucalyptus species to be used as replacements for, or supplements to, mixed southern hardwoods. The laboratory pulping and bleaching aspects of these seven species are discussed, along with pertinent mill operational data. Selected mill trial data also are reviewed.

From biorefineries to bioproducts: conversion of pretreated pulp from biorefining streams to lignocellulose nanofibers

TAPPI Journal ◽  
2019 ◽  
Vol 18 (4) ◽  
pp. 233-241
Author(s):  
CHENGGUI SUN ◽  
RICHARD CHANDRA ◽  
YAMAN BOLUK
Keyword(s):  
Energy Consumption ◽  
Enzymatic Hydrolysis ◽  
Rheological Behavior ◽  
Material Basis ◽  
Softwood Pulp ◽  
Energy Consumptions ◽  
Hardwood Pulp ◽  
The Stability ◽  
Lignocellulose Nanofibers

This study investigates the use of pretreatment and enzymatic hydrolysis side streams and conversion to lignocellulose nanofibers. We used a steam-exploded and partial enzymatic hydrolyzed hardwood pulp and an organosolv pretreated softwood pulp to prepare lignocellulose nanofibers (LCNF) via microfluidization. The energies applied on fibrillation were estimated to examine the energy consumption levels of LCNF production. The energy consumptions of the fibrillation processes of the hardwood LCNF production and the softwood LCNF production were about 7040-14080 kWh/ton and 4640 kWh/ton on a dry material basis, respectively. The morphology and dimension of developed hardwood and softwood LCNFs and the stability and rheological behavior of their suspensions were investigated and are discussed.

Bleaching optimization at WestRock mill in Covington, Virginia

TAPPI Journal ◽  
2016 ◽  
Vol 15 (9) ◽  
pp. 581-586 ◽  
Author(s):  
RICARDO B. SANTOS ◽  
PETER W. HART ◽  
DOUGLAS C. PRYKE ◽  
JOHN VANDERHEIDE
Keyword(s):  
Hydrogen Peroxide ◽  
Sodium Hydroxide ◽  
Chlorine Dioxide ◽  
Capital Expenditures ◽  
Equipment Repair ◽  
Optimization Program ◽  
Hardwood Pulp ◽  
Improved Performance

The WestRock mill in Covington, VA, USA, initiated a long term diagnostic and optimization program for all three of its bleaching lines. Benchmarking studies were used to help identify optimization opportunities. Capital expenditures for mixing improvement, filtrate changes, equipment repair, other equipment changes, and species changes were outside the scope of this work. This focus of this paper is the B line, producing southern hardwood pulp in a D(EP)DD sequence at 88% GE brightness. The benchmarking study and optimization work identified the following opportunities for improved performance: nonoptimal addition of caustic and hydrogen peroxide to the (EP) stage, carryover of D0 filtrate to the (EP) stage, and carryover of (EP) filtrate to the D1 stage. As a result of actions the mill undertook to address these opportunities, D0 kappa factor decreased about 5%, sodium hydroxide consumption in the (EP) stage decreased about 35%, chlorine dioxide consumption in the D1 stage decreased about 25%, and overall bleaching cost decreased about 15%.

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